Earth-Abundant Molecular Z-Scheme Photoelectrochemical Cell for Overall Water-Splitting

Abstract

A push-pull organic dye and a cobaloxime catalyst were successfully co-grafted on NiO and CuGaO 2 to form efficient molecular photocathodes for H 2 production with >80% Faradaic efficiency. CuGaO 2 is emerging as a more effective p-type semiconductor in photoelectrochemical cells and yields a photocathode with four-fold higher photocurrent densities and 400 mV more positive onset photocurrent potential compared to the one based on NiO. Such an optimized CuGaO 2 photocathode was combined with a TaON|CoO x photoanode in a photoelectrochemical cell. Operated in this Z-scheme configuration, the two photoelectrodes produced H 2 and O 2 from 2 water with 87% and 88% Faradaic efficiency, respectively, at pH 7 under visible light and in the absence of an applied bias, equating to a solar to hydrogen conversion efficiency of 5.4×10 −3 %. This is, to the best of our knowledge, the highest efficiency reported so far for a molecular-based noble metal-free water splitting Z-scheme.

Durable photoelectrochemical CO2 reduction with water oxidation using a visible-light driven molecular photocathode

“…33,34 The energy conversion efficiency was 1.7 Â 10 À2 % for 24 h irradiation, which is the highest value reported for full cells using molecular photocatalysts for not only CO 2 reduction but also H 2 evolution. [35][36][37] Table 2 summarizes photocatalyses of the reported non-biased full photoelectrochemical cells, which used a molecular photocatalyst for CO 2 reduction or H 2 evolution, coupled with water oxidation, and our system reported in this paper is also included.…”

Mechanistic insights into photocatalysis and over two days of stable H2 generation in electrocatalysis by a molecular cobalt catalyst immobilized on TiO2

“…25 Separation would lead to control of the direction of electron flow, as it is the case in a PEC cell. [26][27][28] To integrate the high catalytic rates of molecular catalysts in a (so far surface-catalyzed) twocell system, the molecular catalyst must be adsorbed on the electrode. Depending on the substrate, the WRC is either bound via physical adsorption such as hydrophobic interactions 29 or covalently, whereby the anchoring group must be adjusted to the properties of the respective surfaces.…”

Charge-Transfer Regulated Visible Light Driven Photocatalytic H2 Production and CO2 Reduction in Tetrathiafulvalene Based Coordination Polymer Gel

“…Arti cial photosynthesis, i.e., the conversion of sunlight into fuels, is a green approach and has the potential to solve the global energy crisis. In recent years, a signi cant amount of research has been carried out to develop arti cial systems for mimicking the sophisticated methodology of nature's water splitting [1][2][3][4] as well as CO 2 reduction. [5][6][7][8] Natural photosynthesis (NPs) rely on the occurrence of precise sequences of protein/enzymes to the several elementary steps of intercomponent light-absorbing, charge separation, and migration.…”